Good points Kathryn. I used 'game' without quotes in the search because Google would pull up single and plural occurrences. Occurrences were 'Theory of games(s)' was used would also be found. In other words, the search would detect all these options without prejudice, allowing a qualitative assessment of the results. (I tried it with 'games' - without quotes - just to confirm the results were not skewed towards the singular).
Thinking further, I don't put much weight on the actual number of hits. When you are not using quotes for the key phrase, I don't think the actual hit count is of relevance as many hits will be for articles that use the words in a different context. Using the AND boolean operator between words and phrases in quotes can help narrow things down, but I still find irrelevant articles in the search lists.
In a case like this, I take the fact that the term I am thinking of using (which here was 'game theory' in any case) is used in the same context (degree courses in economics) to show that it is a safe translation. I sometimes send myself an email with links to suitable examples for my own reference and, if it has been a difficult decision on what to use, may explain this in a translator's note or cover email to the client. In this case I'd probably use these links:
http://www.york.ac.uk/depts/econ/prospective/grad/courses/ms...http://www.economia.univr.it/fol/main?ent=oi&aa=2007/2008&co...Though, of course, just because an English usage is commonplace, it doesn't mean other possible translations are incorrect. Care is also needed with very specialised language as common usage (of legal terms, for example) may not be the most appropriate. So, in my view, qualitative assessment of search results is more important than quantitative assessment.